Film pull-down mechanism



July 19, 1938. 'A. w. TONDREAU FILM PULL-DOWN MECHANISM Filed Nov. 22, 1935 5 Sheets-Sheet l v INVENTOR. ALBEIPT W. TONDQEAU ATTORNEY.

July 19, 1938. A w TQNDREAU 2,124,322

FILM PULL-DOWN MECHAN I SM Filed Nov. 22, 1955 5 Sheets-Sheet 2 Q 90 INVENTOR. ALBERT W. TONDPEAU J ATTORNEY.

July 19, 1938. w TQNDREAU 2,124,322

FILM PULL-DOWN MECHANISM Filed MN. 22, 1955 5 Sheets-Sheet 4 38 PILOT P/ s Our 0 CZAWS MOVING H 225 P/LoT P/Ns /N CLAWS Movws Dow IN V EN TOR.

ALBEe-r W 7 ONDPAU A TTORNEY July 19, 1 938.

A. w. TONDREAU FILM PULL-DOWN MECHANISM Filed Nov. 22, 1935 5 Sheets-Sheet 5 INVENTOR.

ALaL-m- W Touommu A TTORNEY Patented July 19, 1938 PATENT OFFICE z,1z4.a2z mm PULL-DOWN nmcmmrsm Albert W. Tondreau,

to Warner Bros. Pictures, a corporation of Delaware Glendale, Calif., assignor Inc., New York, N. Y.,

Application November 22', 1935, Serial No. 51,111

13 Claims.

This invention relates to intermittent movement mechanisms, and particularly to intermittent film movements for moving a motion picture film in a step by step motion past the picture gate of a motion picture camera.

The movement comprising the present invention is of the general type in which a pair of claws operate intermittently to engage and pull down the film before the photographing aperture. A pair of pilot or register pins, interconnected with the claws, operate to engage and hold the film in a steady position during the return stroke of the claws. It is of extreme importance'that the film, while it is being exposed, be held perfectly motionless to prevent blurring of the image. Pilot or registering pins have been usedfor some time to attain this result by engaging the these pins prevent longitudinal movement of the film, all prior arrangements of which I am aware. and which include rotating cams or eccentrics to operate the pilot pins, produce a small lengthwise movement .of the pins transversely of the film while in engagement with the film; that is, while the film is being In movements employing eccentrics for and out movement of the pins tinuous while in movements employing rotating cams for this purpose, the pilot pins may remain stationary for a portion of ally about on -half of the During the portion of time, however. the pins dinaliy. Duetothefact that the be a very snug fit in the perforations of the film,

in order to hold the film perfectly motionless long'itudinaiiy thereof during the exposure time. there is generally considerable friction between the pins and the film. Especially is this true where thefilmhasshrunkorotherwisebeendistorted in form or where the intermittent movement has expanded due to bee seen that the sawing action of the pilot pins in and out. while ethe film. tends to move the film back and pins, thus nderstood total exposu e time. the exposure pilot pins must forth along with the it b81118 pressed suchaspressurepads.etc., havebeenusedtoholdthefilmagainstoneof-its thefrictionbetweentbefilmand 'theperforationsmaybcsogreatthatthefilm s5 wlllbcpmbedforwardandbackwardagainstthe operating the pilot plus, this inis practically oonthe time which is usuare being moved longitu It will therefore be action of such spring devices. Furthermore, this sawing action of either the pilot pins or the pulldown claws causes considerable wear in both the film perforations and the member itself as well as tending to produce vibration and noise. 5

One object of the present invention is to minimize the sawing action of the claws and/or pilot pins while in engagement with the film perforations.

This is accomplished by providing a rocking cam to produce an in and out movement of the I claws and/or pilot plus. .Thecam is interconnected with the driving mechanism of the pull down mechanism and is so constructed that a cam follower operating the film engageable member, i. e. claws and/or pilot pins, engages an in-. active portion of the cam while the member is in engagement with the film perforations.

Other features of the invention are the provision of a mechanism whichis simple in construction, capable of high speed, reversible in direction, and that has a fast "pull down" and a long period of "dwell." The above object and features of the invention will be more clearly understood from the following detailed description, reference being had to the accompanying drawings in which:

Fig. 1 is a side elevational view of the pull down mechanism embodying my invention in which the parts are shown as being in position where the film moving claws are in about the middle of their film movement.

- Fig. 2 is a 'vlewsimflar to that of Fig. l, partly broken off, showing the film moving claws in about the middle-of their return movement.

Fig. 3 is a sectional elevation view taken along the line H of Fig. 1.

Fig. 4 is a sectional plan view taken along the line 4-4 of Fig. l. mg. 5 is a sectional view through the shuttle fork and is taken along the line 5-5 of Fig. 1.

Fig. 6 is asectional elevation view of the rear guide plate taken along line H of Fig. 2.

Fig. 'l is a plan sectional view of the locking 5 means for holding the aperture plate in closed or threading position and is taken along the line |-.-1 of Fig. 2.

Fig. 8 is a transverse section partly broken off of the flexible fill-W eel.

Pigs. 9-11 are tic views showing the pull down mechanism in various positions.

Fig. 12is a ticviewof amodified form of the invention.

'l 'igs. 18 and. are tic-views of a ll guide plate comprising the film guiding means.

Both the aperture plate 4 and the guide plate I are mounted upon a rear wall 8 at; right angles thereto. The rear wall 8 which supports the pull down mechanism proper is adapted to be mounted in any suitable manner, such as by screws I, within the casing of 'a motion picture camera (not shown) and thus operate in conjunction with a suitable shutter mechanism and with a suitable arrangement of lenses as is apparent to one familiar with the art. The film engaging claws 8 and 8 (Fig. 5) have their ends formed so as to engage the sprocket hole perforations provided along either side of the film I and are attached by means of nuts l8 and H to the cross head i2 of a film advancing member or shuttle fork l8. The claws 8 and 8 operate within elongated slots l4 and I5 (Fig. 6) provided in the rear guide plate 5 and also extend a short distance into similar and registering slots I 8 and I1 (Figs. 1 and 5) provided in the aperture plate 4.

The claw or shuttle fork actuating mechanism is divided into two parts, one for efiecting the up and down motion of the claws 8 and 8 and the other for effecting the in and out motion of the same claws at the limits of their up and down motion. Both of these movements are actuated by an eccentric disk l8 having a crank pin l8 mounted thereon.

A connecting rod 28 having one end journaled on the crank pin I9 is slidable within an elongated bearing portion 2| provided on a rocking bearing member 2| as clearly shown in Fig. 5. The member 2| has an enlarged bearing portion 22 which is joumaled within the wall 8. The outer end of the member 2| is journaled within a bushing 23 secured within a bracket 24 which is in turn, secured by screws 24' (Fig. 6) to the wall 8. A pair of washers 25 and 25' on either end of the bushing 28 engage a shoulder 21 on the member 2| and a nut 28 respectively, the nut 28 being mounted upon a threaded end portion 28 of the member 2| to prevent axial movement of the member. The forward end of the member 2| is provided with an elongated bearing portion 88 to slidably receive a rectangular shank 8| of the shuttle fork l8. Thus it will be seen that the rotation of the eccentric |8 causes the connecting rod 28 to produce a rocking motion of the bearing member 2| and in turn will cause the claws 8 and 8 of the shuttle fork l8 to be moved 8 through an arc concentric with the bearing member 2|. It is this motion of the claws which pulls the film downward past the picture aperture I provided in the aperture plate 4 (Fig. l)

Describing now the means for moving the claws 8 and 8 in and out of engagement with the film, a second connecting rod 82 (Figs. 3 and 4) is also journaled at one end upon the crank pin l8. The other end of the connecting rod 82 is pivotally mounted as at 88 (Figs. 1 and 3) to a crank arm 84 which is secured by a pin 84* to a rocking shaft 88. The shaft 88 is journaled within a bearing member 88 secured to the rear of the wall 8 by means of screws 88'. The inner end of the shaft 3 is provided with a rocking cam 81. The cam8'l engages a cam follower 88 having circular supporting studs 88 and 88' (Fig. 1)

projecting on either side thereof which are slidably carried within bearings 48 and 48. Bearings 48 and 48' are secured to the front of the wall 8 by means of screws 4| and held in alignv siidably carried within a rocking bearing 48 mounted on a boss 48 on the forward edge of the cam follower 88. The lower end of the link 48 is siidably carried within a rocking bearing 48 which projects through an elongated opening 88 in a cover plate 8| provided at the forward edge of the bearing 82 and is secured to the shank 8| of the shuttle fork l8 as shown at 82 (Fig. 5). Cover plate 8| is secured to-the forward end of the bearing 82 by means of screws such as 58 (Figs. 4 and 6).

Register pins 84 and 88 are provided above the claws 8 and 8 and are adapted to slide within bearings and 81 formed integrally with the rear guide wall 8. The ends of the pins and 58 .are of the same shape and size as the ends of the claws 8 and 8 and are adapted to engage and hold the film in position before the film aperture I (Fig. l) of the aperture plate 4 while the claws 8 and 8 are returning on their upward stroke. Pins 84 and 88 are secured at their rear ends by means of nuts 88 to a cross head 88 which, in turn, is secured by a screw 88' to the forward end of a link member 8|. The member 8| is secured at its rear end to a boss 82 (Fig. 4) provided on the cam follower 88 by means of a screw 88. Thus it will be seen that forward motion of the cam follower" will effect a similar motion to the register'pins 84 and 88 and at the same moment will effect a rearward motion through the link 48 to the claws 8 and 8 and vice versa.

Referring now to Fig. 5, the crank pin |8 of the eccentric disk I8 is lubricated by means of lubriand its associated springs 14 to lubricate the connecting rod 28.

. As was stated before, one object of the invention is to obtain a fast pull down and a comparatively long "dwelP of the film. This is accomplished by rotation of the eccentric disk |8 in a clockwise direction as indicated by the arrow A (Figs. 1, 2, and 9). When the claws 8 and 8 are moving the film downward as in Figs. 1 and 9, the length of the lever arm between the crank pin l8 and the center'of the bearing member 2| is relatively shorter in comparison to the lever arm between the member 2| and the ends of. the claws 8 and 8'than when the claws are moving in their upward return motion as in Fig. 2, thus insuring a faster downward movement and a comparatively slow return. In the operation of the device, reference is to be had to Figs. 9, 10, and 11. The circle 8 is the circle of eccentricity of the eccentric pin l8. While the pin l8 moves from points to b in the direction of arrowv A the claw member 3| will be moving downward in its film moving stroke whereas from b to c the member 3| will be moving upwardly in a disengaged return stroke. It will be seen, therefore, that due to the longer arc of travel of the pin I9 on the return stroke, the film will be given a starting on its upward stroke.

of the registering pins 54 relative to the film durclaw member 3|.

ing the major portion of the exposure.

Referring now to Figs. 1 and 6, it will be noted that the rear film guide wall 5 is apertured at 22 opposite the picture aperture III to receive a pressure roller assembly 13 slidabiy therein. Assembly 13 comprises a pair of rollers 1| and 15 rotatably mounted within a cage 16 which is resiliently pressed against the film I passing through the aperture plate 4 by means of a spring 11 secured to the rear of the guide wall 5 by means of a screw 13.

The aperture plate 9 is pivotally mounted at its upper end to the wall 9 by means of a stud 19. Referring now to Figs. 1 and 7, it will be noted that the lower end of the aperture plate 4 is provided with an elongated slot II through which projects a stud 32 secured to the rear wall 9 by means of a nut 22'. The forward reduced end portion 8| of the stud 32 has a pin 93 projecting transversely through it which is adapted to be engaged within a bayonet slot indicated at ll provided on a sleeve member 95. A handle 35' on the member 3| allows for rotation so as to lock a conical shoulder 39 upon a similar shaped seat 31 of the aperture plate 4. By releasing the sleeve member 24, the aperture plate may be swung forward into the position shown by the dotted lines 33 in Fig. 1 to thus allow for threading or removal of the film within the picture gate and also to allow for cleaning the film passages. A sleeve member II2, similar to that of 95, is provided on the upper stud 19' to retain the aperture plate thereon. I

Fig. 12 .is a diagrammatic view of a modified form which is similar to that shown in Figs. 9 to 11 except that the cam 31' is adjusted to a diiferent angular position in relation to the arm 34' in which case the inactive portion 31'a is in contact with the cam follower 33' during the downward film advancing stroke of the pull down -In this particular form sawing action between the film claws and the film perforations is prevented during the film advancing stroke.

Figs. 13 and 14 are diagrammatic views of a further modified form of pull down mechanism in which sawing action is prevented on engagement of the film by .both the pull down claws and the pilot pins. In this arrangement a cam I2. is actuated by an arm 34" rod 32" by an eccentric I!" in a manner similar to that shown in Figs. 9 to 12. Cam I29 pivots about a point |2| and has a second cam I22 rotatably secured inany suitable manner thereto to also rotate about the point I2I. Cam I22 engages a rectangular cam follower I23 rigidly provided upon the upper end of a link member I24. Member I24 is pivotaily mounted at I25 upona stationary support (not shown) and engages at through a connecting its lower end the claw member 3|" to impart I cam follower I26 which is slidable horizontally within bearings I21 and I21 and is rigidly connected to the pilot pins 54''. The cam I22 is also so angularly adjusted that during the film engaging stroke of the pilot pins the inactive portion I22a of cm I22 will be in engagement with cam follower I26 thus preventing movement during that portion of the cycle. Fig. 13 shows the claw member 3|" at the beginning of its return stroke, traveling in the direction of the arrow A. At this point the pilot pins El" have fully engaged the film I" and will remain in this position until the eccentric l9" reaches the point a after which the pins 5|" will begin to disengage. At this time the pull down claws 9" will begin to enter the film perforations. By the time the eccentric has traveled from point I to g the pilot pins 54" will be completely disengaged and the pull down claws completely engaged and ready to advance the film downward. Fig. 14 shows the claw member 3|" half way through its film advancing stroke and traveling in the direction of arrow B. The pilot pins SI" are now at their fully retracted position. When eccentric 19" reaches point It the pull down claws stroke, ready to be pins 54" are about ready toengage tions'. During the travel. of eccentric I9" from h to j the pilot pins 54" engage the film perforations and the claws 9" are disengaged.

Referring now-to Figs. 4 and 8, it will be noted that the eccentric disk I3 of the pull down mechanism is driven through a, flexible flywheel generally indicated at '9. A spindle 9|Icarrying the eccentric disk i8 at one end and the flywheel 99 at the opposite end is iournaled within a bearing 9| provided in the wall 92 forming part of the camera casing. a disk 93 secured to the spindle 90 by a key 93' andhas a relatively heavy rim 94 secured thereto by means of bolts 35. A second disk is provided adjacent the second shaft 91 coaxial with the spindle 90. The shaft 91 is journaled at one end within bearing rim 94 and is secured to a,

9" are at the end of their I disengaged while the pilot the perfora- .45 The flywheel 39 comprises 93 and at the other end within a ball bearing 99 counter-bored holes I06 of The screws I31 are threadably mounted within the rim 94 of the flywheel 39. A spiral gear Ill secured upon the shaft 91 meshes with another spiral gear I99 mounted on a motor drive shaft III. In balancing the flywheel and the accompanying pull down mechanism, a mark is placed on the outer edge of the rim 94 of the flywheel 89 and while rotating the flywheel. is viewed through a strobosc pe (not shown). The tension of the springs in and I32 is then adjusted by'means of the screws "1 until the mark upon the flywheel appears to be stationary 93. Connection between Ill having heads I05 which in the strobo 'gear teeth around its periphery through which the shutter and other ancillary mechanism may be driven.

Having thus described the invention, what is claimed as new and desired to secure by Letters Patent, is:

1. A film pull down mechanism comprising the combination of a film advancing member, a rocking slide bearing for said member, an eccentric, a drive shaft for said eccentric, a connecting member slidably connected to said bearing and pivotally connected to said eccentric, meansfor imparting an oscillating motion to said film advancing member under control of said connecting member, a second connecting member pivotally connected to said eccentric, a cam, an operative connection between said second connecting member and said cam, a cam follower for said cam and an operative connection between said cam follower and said film engaging member for imparting a fihnengaging and disengaging motion to said film advancing member.

2. A film advancing mechanism comprising the combination of a film advancing member, a pivotal slide bearing for said member, a rotating member having an offset portion thereon, a connecting member slidably connected to said bearing and engaged by the offset portion of said rotating member, means for imparting an oscillating motion to said film advancing member under control of said connecting member, a cam, a cam follower, an operative connection between said cam follower and said film advancing member for transmitting a film engaging and disengaging motion to said film advancing member, a second connecting member engaged by the ofiset portion of said rotating member, and an operative connection between said cam and said second connecting member for oscillating said cam.

3. A film pull down mechanism comprising the combination of a film advancing member, a rocking bearing for said member, said member being slideable in said bearing, an eccentric, a connecting rod pivotally connected to said eccentric and slideably connected to said rocking bearing for imparting an oscillating movement to said' film advancing member, a second connecting rod pivotally connected to said eccentric, a cam, an operative connection between said second connecting rod and said cam, a cam follower for said cam, a register pin member operated by said cam follower and a link between said cam follower and said film advancing member for imparting in and out motion to said mechanism.

4. In a motion picture film advancing mechanism the combination, with a film guide, of a film advancing member adapted to engage and advance a film in said guide, an eccentric, means for transmitting motion from said eccentric to said film advancing member for pulling down said member, a cam,.a connecting rod connecting said eccentric to said cam for imparting an oscillating motion to said cam, a cam follower for said cam, and a connection between said cam iollowerandsaidfilmadvancingmembertoimpart a film engaging and withdrawing motion to said member.

5. A film advancing mechanism for motion picture apparatus comprising the combination of a film guide, a film advancing member adapted to intermittently move a fihn in said guide, an eccentric, an operative connection between said eccentric and said member for pulling down said member, a cam, an arm connected to said cam, a link connection between said arm and said eccentric, a cam follower connected to said member and adapted to be engaged by said cam for imparting a film engaging and disengaging motion to said member. jr 6. A film pull down mechanism comprising th combination'of a film guide, a film advancing member adapted to intermittently move a film in said guide, a sliding rocking bearing for said member, an eccentric for rocking said member about said bearing, a cam operated by said eccentric, a cam follower adapted to be positively actuated in opposite directions by said cam, and an operative connection between said cam follower and said member for reciprocating said member.

7. A film advancing mechanism comprising the combination of a film advancing member, a film registering member, an eccentric,.means for rotating said eccentric, a cam, a link connection between said eccentric and said cam for oscillating said cam, a cam follower for said cam. an operative connection between said follower and said film advancing member for engaging and disengaging said film advancing member with the film, a second cam connected to said link connection, a cam follower for said last mentioned camand an operative connection between said last mentioned follower and said film registering member.

8. A film advancing mechanism comprising the combination of means providing a film path, a film advancing membertherefor, a film registering member, an eccentric, a cam, rotatable driving means, a link connection between said eccentric means and said cam for oscillating said cam, means interconnecting said cam and said film advancing member for moving said film advancing member into and out of said path, means interconnecting said eccentric and said film advancing member for imparting a film advancing stroke to said film advancing member while in engagement with said film, a second cam, means connecting said second cam ,with' said link con nection for oscillating said second cam, and means interconnecting said second cam; and said film registering member for moving said film registering member into and out of said path.

9. A film advancing mechanism comprising the combination of a film advancing member, a film registering member, a pair of cams, respective cam followers opcratively connected to said film advancing member and said film registering member, said respective cam followers engaging respective ones of said cams, an eccentric, means for rotating said eccentric, and a link connection between said eccentric and said cams for oscillating said cams about a fixed point.

10. A film advancing mechanism comprising the combination of a film advancing member, a film registering member, a pair of cams having acti e and inactive portions thereon, respective cam followers operatively connected to said film advancing member and said film registering member, said respective cam followers engaging respectiveonuoisaidcamsiorimpartingafilmengaging motion tosaid members. an eccentric, and a link connection between said eccentric and said cams foroscillating said cams, said inactive portions of said respective cams engaging said respective cam followers when said respective members are in film engaging position.

11. A motion picture film advancing mechanism comprising a film advancing member, an eccentric, a pair of independently movable connecting rods, means for pivotally connecting both of said rods fixedly to said eccentric, cam means between one of said rods and said member for controlling the film engaging and disengaging motion of said member and means for controlling the film advancing motion of said member by the other of said rods.

12. A motion picture film advancing mechanism according to claim 11 wherein both of said rods are pivotally connected to the same point on said, eccentric;

13. A film pull down mechanism comprising the combination of a film advancing member, a film registering member, a rocking slide bearing for said film advancing member, an eccentric, a

connecting member pivotaliy connected to said eccentric, means interconnecting said film advancing member and said connecting member for imparting an oscillating motion to said film ad vancing member under control of said connecting member, a cam, a second connecting member plvotally connected to said eccentric, an operative connection between saidsecond connecting member and said cam, a link, a pivotal support for said link, a cam follower on said link and operatively connected to said cam, an operative connection between said link and said film advancing member for producing a film engaging and disengaging motion to said film advancing member, a second cam operatively connected to said second connecting member, a cam follower for said second cam and an operative connection between said last mentioned cam follower and said film registering member.

, ALBERT W. TONDREAU. 

